Walk-in type coolers, such as those commonly found in convenience stores, are typically constructed of thermally insulated panels that are fastened snuggly together to form interlocking side walls, ceilings and floors. The panels are usually comprised of foam insulation, such as expanded polystyrene and polyurethane, which are encased within thin metallic sheets. The panel ends are shaped to fit together in tongue-and-groove fashion and are provided with latch means for drawing and holding them snuggly together. These ends are not covered by the sheet metal so that their exposed tongues and grooves may be snuggle interfitted.
Metallic cases have been required to provide the panels with structural integrity since foam polystyrene and polyurethane, while possessing good thermal insulative properties, have little structural strength and can be easily fractured. The provision of metal casings, however, such as those formed from sheet aluminum, has rendered the panels costly to manufacture, heavy, and difficult to assemble. As previously stated, gaps in the metal casings have had to be provided to permit adjacent panels to be securely interfitted. Thus, prior to assembly the surface areas of the foam polymer cores have had to be exposed thereby rendering them subjectable to damage prior to assembly and erection. Assembly, whereby both a good interlock is achieved between the foam tongues and grooves as well as the metal casings, has been difficult to achieve consistently in the field. In addition, the metal casings have rapidly oxidized and deteriorated along their bottoms that are normally in direct contact with alkaline concrete flooring.
Accordingly, it is seen that a need exists for a thermal insulation panel of the type that may be used as components of cooler walls of a simplified, more economical type to manufacture and assemble and that does not rapidly oxidize and deteriorate. It is to the provision of such a panel therefore that the present invention is directed.